Oncotic Pressure

Like the Starling’s forces in every capillary in the body, the effect of oncotic pressure on the hydrostatic pressure must be taken into account. That is, the blood flowing into the glomerulus contains plasma proteins and blood cells that displace the water content of the blood. This creates, in effect, a counter force called oncotic pressure, as water outside the capillaries seeks to equalize with the water inside the capillaries through osmosis.

However, the force of the hydrostatic pressure pushing filtrate out of the glomerulus is, in effect, greater than the force of oncotic pressure that draws it in.